[core] place symbol layers in correct order

Previously, the placement of symbols depended on the order in which the
glyphs they need were loaded. The placement order should be based on the
style.

To fix this, symbol layers are placed in `placementPending` after they
are parsed. After all layers are parsed, symbol layers (stored in
`placementPending`) are placed and returned.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/mbgl/map/tile_worker.hpp b/src/mbgl/map/tile_worker.hpp
index 74894a9eb8..a5e892e2b6 100644
--- a/src/mbgl/map/tile_worker.hpp
+++ b/src/mbgl/map/tile_worker.hpp
@@ -53,7 +53,7 @@ public:
                                    const GeometryTile&,
                                    PlacementConfig);
 
-    TileParseResult parsePendingLayers();
+    TileParseResult parsePendingLayers(PlacementConfig);
 
     void redoPlacement(const std::unordered_map<std::string, std::unique_ptr<Bucket>>*,
                        PlacementConfig);
@@ -61,6 +61,7 @@ public:
 private:
     void parseLayer(const StyleLayer*, const GeometryTile&);
     void insertBucket(const std::string& name, std::unique_ptr<Bucket>);
+    void placeLayers(PlacementConfig);
 
     const TileID id;
     const std::string sourceID;
@@ -74,12 +75,15 @@ private:
     bool partialParse = false;
 
     std::vector<std::unique_ptr<StyleLayer>> layers;
-    std::unique_ptr<CollisionTile> collisionTile;
 
     // Contains buckets that we couldn't parse so far due to missing resources.
     // They will be attempted on subsequent parses.
     std::list<std::pair<const SymbolLayer*, std::unique_ptr<Bucket>>> pending;
 
+    // Contains buckets that have been parsed, but still need placement.
+    // They will be placed when all buckets have been parsed.
+    std::unordered_map<std::string, std::unique_ptr<Bucket>> placementPending;
+
     // Temporary holder
     TileParseResultBuckets result;
 };